Compact laser with radial polarization using birefringent laser medium

We demonstrated the generation of a radially polarized laser beam using the birefringence of a c-cut Nd:GdVO₄ laser crystal. Compared with a previous work using a long Nd:YVO₄ crystal, an improvement of the power efficiency and a reduction of the cavity size were achieved. A larger expansion of the cavity length for an extraordinary ray due to the positive birefringence of the crystal was numerically evaluated on the basis of ray optics and the vector diffraction theory.